Electric circuit interrupter



2 Sheets-Sheet 1 Filed Feb. 20, 1955 Invent or: Conrad J. Bal entine,

by His Attorney Sept. 6, 1955 c. J. BALENTINE ELECTRIC CIRCUITINTERRUF'TER 2 Sheets-Sheet 2 Filed Feb. 20, 1953 Fig.7.

Jim i F'igJl.

Inventor: Con rad J. Balentine, by W? @411;

His Attorney.

United States Patent Ofice 2,717,294 Patented Sept. 6, 1955 ELECTRICCIRCUIT INTERRUPTER Conrad J. Balentine, Philadelphia, Pa., assignor toGeneral Electric Company, a corporation of New York Application February20, 1953, Serial No. 337,997

2 Claims. (Cl. 200150) My invention relates to electric circuitinterrupters and more particularly to high speed circuit breakers of thefluid-blast type for opening alternating current power circuits within afew half cycles.

More specifically, my invention constitutes a further development,improvement, and simplification of the general type of circuitinterrupter disclosed in my U. S. Patent 2,545,334, which is assigned tothe assignee of the present application.

It is a continuing objective in oil-blast power circuit breaker designto reduce arcing times so as to obtain, among other advantages, areduction in contact erosion and in oil deterioration. This desiredobjective has been attained in my invention by designing the interrupterin such a manner that a high degree of control over the arc and thepressure generated by the arc is obtained.

In accordance with my invention this desired degree of control has beenachieved, in part, by constructing the batfie stack, usually associatedwith this type of fluid-blast interrupter, of a novel form whereby it issectionalized into an upper and lower chamber by a division bafiie. Theupper and lower chambers, through which a single arc may be drawn, havefeatures which cooperate with the division bafiie in such a manner thatthere are provided upper and lower arc-extinguishing agencies arrangedclosely in series, the upper agency being especially adapted to promoterapid interruption of extreme large and extreme small current arcs andthe lower agency being especially adapted to promote the rapidinterruption of medium current arcs.

It is a principal object of my invention to provide a new, simplified,and improved circuit interrupter which effects more rapid arc extinctionby a closer control of the arc and the arc-generated pressure within theinterrupter.

It is another object of my invention to insure that the single are isinitiated and maintained in the precise location within the interrupterwhere it is most vulnerable to extinction by the fluid blast.

It is still another object of my invention to form the exhaust vents ofthe interrupter unit of such relative sizes that those difiicultiesusually associated with the interruption of the extreme high and lowcurrents of the interrupting range are avoided to a large degree.

Further objects and advantages of my invention will become apparent asthe following description proceeds, and the features of novelty whichcharacterize my invention will be pointed out with particularity in theclaims annexed to and forming a part of this specification.

In the drawings, Fig. 1 represents a sectional view taken along the line1--1 of Fig. 3;

Fig. 2 is a perspective view partly in section of the bafile stack ofFig. 1;

Fig. 3 is a sectional view taken across the top of the bafiie stackalong the line 3-3 of Fig. 1;

Fig. 4 is a plan view of one of the venting bafiles as seen from line 44of Fig. 1;

Fig. 5 is a plan view of another of the baflies, the division baffle, asseen from line 55 of Fig. 1;

Fig. 6 is a plan view of still another of the venting baffles as seenfrom line 6-6 of Fig. 1;

Fig. 7 represents a second embodiment of my invention as seen in anelevation view partly in section taken along the line 77 of Fig. 8;

Fig. 8 is a perspective view partly in section of the baffle stack usedin Fig. 7;

Fig. 9 is a plan view of one of the venting baffles as seen from line 99of Fig. 7;

Fig. 10 is a plan view of another of the baffles, the division bafile,as seen from line 1010 of Fig. 7;

Fig. 11 is a plan view of still another of the venting baflies as seenfrom line 1111 of Fig. 7.

The embodiment of my invention disclosed in Figs. 1-6 for conveniencemay be identified as the lower voltage design, whereas the embodimentdisclosed in Figs. 7-11 may be identified as the higher voltage design,although tests have shown that both operate almost equally well for thegreater part of the interrupting range over which such devices, singiyor by compounding, are usually applied, say 15-330 kv.

The interrupting unit shown in Fig. 1 is adapted to be mounted, alongwith another similar unit (not shown), inside a relatively largeoil-filled enclosing tank of a conventional tank-type circuit breaker.These two interrupting units would cooperate with a reciprocating bladecontact (not shown) such as is disclosed in U. S. Patent 1,548,799 toHilliard, which is assigned to the same assignee as the presentapplication.

With reference to Fig. 1, the interrupting unit is supported within theoil-filled tank from a conductor stud 1 of an inclined electric bushing,being secured thereto by suitable clamping means indicated generally at2. An adapter 3, which forms a part of the interrupting unit, isconstructed and arranged in a well-known manner to support theenclosing, pressure-confining casing 4 by means of studs 5, supportingring 6 and shell 7. More particularly, shell 7 has internal threads awhich cooperate at 8 with mating threads formed on casing 4. Thesupporting ring 6 rigidly carries studs 5 passing through suitableapertures in adapter 3 and has external threads meshing with the threadsof shell 7. Thus, by tightening clamping nuts 10, which are applied tothe ends of the studs 5, the casing 4 may be rigidly secured to andsupported from the adapter 3 and conductor stud 1.

A baflie stack 11 is rigidly mounted within casing 4 by means ofcylindrical spacer sleeves 12 and 13 held against opposite ends of thebaffie stack 11 by a throat member 15 and adjustable clamping ring 16.The throat member 15 may be secured in place within the casing 4 byconventional means such as dowel pins 17. The adjustable clamping ring16 has a threaded periphery which cooperates with the threads 9 on shell7 to provide an adjustable means for compressively retaining sleeves 12and 13 and baffle stack 11 against the fixed throat member 15.

The contact structure disposed within the casing 4 comprises astationary contact assembly generally indicated at 29 and a rod-typemovable contact 21, which is shown in open position in Fig. l. Thestationary contact structure is a tulip-type cluster of contact fingers22 which are generally conventional except for an arrangement of arcingtips or electrodes 23 which are applied to certain of the contactfingers 22 for a special purpose to be described in greater detailhereinafter. In a conventional manner, the fingers 22, which may betipped with arc-resistant material as shown at 220, areradially-inwardly biased by suitable spring means 24 interposed betweenthe fingers 22 and a contact retainer 25 so that these fingersresiliently embrace with appropriate pressure the reciprocable contact21 when the interrupter is in closed position. Suitable flexibleconnecting braid 26 assures that electrical contact will be maintainedbetween the fingers 22 and the adapter 3.

The baffle structure 11 comprises a plurality of superimposed insulatingbaffies or plates U, A, B, C, D, E, and L, which may be rigidly boltedtogether to con stitute a sub-assembly as in Fig. 2. These baffles areformed with cooperating central apertures which define a main,axially-extending arc passage 27 for the are which is drawn when themovable contact 21 is with drawn at high speed from the fixed contactassembly 20. In addition, the bafiies have cooperating apertures whichdefine passages for controlling the arc-generated pressure and fordirecting a cross-blast of fluid into the path of the are. Moreparticularly, the baffle stack comprises a top baffie U shoa n in F s 2and 3: baflies A adjacent thereto and shown detan in rig. bal'llesdetail in B, each of which is simply baffle A laid on its reverse face;division bafiie or barrier C shown in detail in Fig. 5; baflle D whichis identical to baffie A except that the central arc passage opening ofbaflle D is smaller than that of baffle A; baffie E which is shown indetail in Fig. 6; and a lower bafiie L which comprises the ported bottomplate of the stack sub-assembly. Division bafile C divides the bafllestack 11 into what may be termed an upper and a lower pressure chamber.With the baffles arranged in the order described above, the main arcpassage 27 in the upper chamber has a bore 28 substantially differentfrom the bore 29 of the lower chamber. In the lower voltage design ofFigs. 1-6, the upper bore 28 is substantially larger than the lower bore29, the latter having a relatively small clearance about the rod contact21. This feature of different size bores for upper and lower portions ofthe main arc passage forms a con tributory important part of myinvention which is explained in greater detail hereinafter.

As may be seen in the drawings, all of the abovedescribed bafiles areformed with registering hole or slottype apertures which collectivelydefine the vertical blast duct 32 disposed at one side of the arcpassage 27. At a generally opposite side of the arc passage 27 thebattles A and B are respectively formed with opened end slots 28a and23b and closed end slots 29a and 2% associated in V relationship in amanner similar to that shown in my above-mentioned U. S. Patent2,545,334. These slots 28a and 22b define divergent supplementaryarc-confining passages 40 and 41 terminating in a pair of offset orangularly displaced vents 42 in the upper chamber. In a correspondingmanner, baffles D and E of the lower chamber of the baffie stack areformed with opened end slots 28d and 282 and closed end slots 29d and292. These slots in the lower chamber are associated in v relation inthe same manner as the slots of the upper chamber and define divergentsupplementary arc-confining passages 30 and 31 terminating in a seriesof offset vents 34 in the lower chamber. From Fig. 2 it will be seenthat the divergent arc-confining passages 40, 41 in the upper chamberare in substantial angular alignment with corresponding arc-confiningpassages 30, 31 in the lower chamber. Similarly, corresponding exhaustvents 34 and 42 of the two chambers are in substantial angular alignmentdown the sides of the baffle stack. It should be noted that exhaustvents 42 in the upper chamber are made comparatively large in relationto the exhaust vents in the lower chamber for reasons to be explained ingreater details hereinafter. The bafile stack vents 42 and 34 registerwith vertically extending exhaust ports 35 formed in the casing 4 toprovide for immediately discharging the ionized products of arcing intothe surrounding cool un-ionized oil.

The operation of the interrupter is as follows. When the circuit breakeris tripped open, the movable contact 21 is rapidly withdrawn from itsclosed position toward the position of Fig. 1. This downward movement ofcontact 21 initiates an are between the fixed and movable contacts. Thisare reacts with the immediately surrounding oil to generate within theupper portion of the battle stack a gaseous bubble, the pressure fromwhich drives fluid down the blast duct 32 and transversely across thepath of the are as said are is drawn by the moving contact tip into thelower chamber. The flow pattern is generally indicated by the arrows 33of Figs. 1 and 6. This cross-blast of fluid is eflective to rapidlyextinguish the arc, since it bows the are into an arc confining passage30 or 31, as illustrated at 36 in Fig. l, in which position the arc iseffectively elongated about the division bafiie C, which forms a barrierbetween the upper and lower supplementary arc-confining passages, and issubjected to a highly intensified cross-blasting action. The fluid blastsweeps the are products out into the sur rounding dielectric fluidthrough the vents 34 and exhaust ports 35. The divergent passages 30 and31 constitute pockets for holding the arc entrapped therein for blastingby the arc-extinguishing fluids. The closed ends of the slots 29d and292 constitute arc retaining barriers which, nevertheless, do notprevent the flow of arc gases from within the arcing passage 27, so thatthe latter may be immediately filled with fresh dielectric fluid afterthe arc is extinguished at a current zero.

Since it is apparent from the above description that the arc is mostvulnerable when displaced sidewise into a divergent pocket 30 or 31, Iencourage the are from its inception to assume this favorable displacedposition by providing an extended arcing tip 23 for each of the twostationary contact fingers 23 which lie in vertical and angularalignment with the two legs of the V pockets. Thus the arc is drawn atleast from one or the other of these tips for displacement immediatelyinto a favorable pocketed position either for obtaining instant blastingand pressure relief through the larger upper vents 42 in the case ofheavy current arcs; or, in the case of lighter current arcs, of beingdrawn further into the lower chamber below the division bafile C anddisplaced by crossblast action for venting through the smaller lowervents 34. Such a lighter, or medium current are might be as indicated bythe wavy dotted line 36 in Fig. 1. For receiving the arcing tips 23therein, short slots 37 in registering relationship with the legs of theV pockets are provided in the upper bafile U as seen in Fig. 2.

Although the presence of the division barrier in producing the steppedchange in the bores of the upper and lower chambers inherently improvesthe creepage path conditions along the sidewalls of the arc passage,thereby to minimize restriking of the extinguished arc, the chieffunction of the barrier is to afford two arc-extinguishing agenciesarranged closely in series.

Thus, for very heavy current interruptions intense pressure is generatedwhich can relieve itself immediately through the large vents 42 so thatthe arc explosively can blast itself out while the central opening inthe division bafiie is yet substantially closed off by the rod contact.Excessive pressures also may find additional relief through the bore 38of the tubular rod contact 21. During this interruption of heavycurrents the division bafile C, through its cooperation with contact 21,substantially closes off the vents 34 of the lower chamber, therebypreventing too rapid dissipation of the arc-generated pressure in theupper chamber.

For medium current arcs, however, lower pressures are generated and thearc will continue to be drawn downwardly into the lower chamber where itwill be subjected to the cross-blast action of the fluid displaced fromthe upper chamber through the aperture 32 in the division baffle C, andout through the smaller vents 34, as indicated by the flow arrows 33. Ithas been found by tests that the relative sizes of the vents 34 and 42is most important, so that in conjunction with the stepped change fromthe upper chamber to the lower chamber afforded by the division baffle,the interrupter of my invention also requires the combination of thesuddenly stepped-down exhaust vents from a large area in the upperchamber to a comparatively small venting area in the lower chamber, e.g., where the two larger vents 42 are rectangular aperturesapproximately x /z; the smaller vents 34 are /8" X A or the area. Sincethe large current arcs are interrupted in the upper chamber, aspreviously explained, the lower chamber is generally required to handleonly medium and low current arcs, that is, arcs of lesser diameter thanthe high current arcs interrupted in the upper chamber. In order toeffectively provide for such smaller arcs, the vents 34 of the lowerchamber must be relatively small so as to effectively confine the arewithin a supplementary arc passage or 31 so that it is prevented frombeing looped outward through the vents 34 and established exterior tothe baffle stack. Thus, these large and small vents may be considered asconstituting appropriate venting apertures adapted for large and smallcurrents respectively, where large and small current arcs are thought ofas having commensurate physical diameters.

The large initial vents 42 not only are favorable for extreme highcurrent arcs, as previously described, but are also favorable forextreme low current arcs. For example, during such low currentinterruptions, large initial vent openings like those at 42 will permitthe ready influx of oil from the surrounding oil-filled tank, therebyfilling up the space induced by the rapidly receding movable contact 21,which is producing but a comparatively weak arc and a resulting lowpressure. rent arcs may persist until they are drawn by the movingcontact into the sub-chamber provided for this purpose between thebaffle stack and the throat member 15' of the interrupter casing.Pressure generated in this sub-chamber may produce fluid flow upwardtherefrom into the blast duct 32 to aid in the cross-blast representedby the arrows 33. invariably the circuit is interrupted before the tipof the rod contact 21 leaves the interrupter.

From this description of the operating features of my interrupter, itshould be apparent that I have provided a I shown in Figs. 7-1l isconstructed in a manner very much similar to the embodiment of Figs.1-6. The only practical difference between these two embodiments is thatin the device of Figs. 7-11 the main arc passage has its upper portion51 of a substantially smaller bore than the lower portion 52, instead ofvice versa, as in Figs. 1-6.

As may be seen from Figs. 7 and 8, the baffle stack 53 comprises aplurality of baflle plates U, A, B, C, D, E, F, and L, bolted togetherand sectionalized into an upper chamber 54 and a lower chamber 55 bydivision baflle C. Suitably registering apertures in the superimposedbaflies define a vertical blast duct 56, divergent supplementaryarc-confining passages 57 and 58 in the upper chamber, and divergentsupplementary arc-confining passages 59 and 60 in the lower chamber inthe same manner as described in connection with the first embodiment.

To open the circuit, movable contact 61 is rapidly withdrawn from fixedcontact assembly 62, thereby drawing an are between the two contacts.Depending upon the value of current being interrupted, the arc may beSuch light curdrawn through the successive regions of the interrupter asalready explained. Since this blast action is almost identical to thatdescribed with respect to Figs. l-6, no further detailed description isconsidered to be necessary. The cross-sectional area of the vents 63 and64 in the upper chamber is substantailly greater than thecross-sectional area of the vents 65 and 66 in the lower chamber. Thisdifference in cross-sectional area of the vents contributes to the sameresult as described in connection with Figs. 1-6. Similarly, arcing tips65 are received in slots 67 in the same manner and for the same reasonsas described with respect to arcing tips 23 (Figs. 1 and 3).

The division baffle C cooperates with the structural features of theupper and lower chambers 54 and 55 to carry out substantially the samefunctions as attributed to bafiie C in Figs. l6. Although it might belogical to suppose that the second-described interrupter embodiment ofFigs. 7-8 is the more appropriate for the higher voltage application inthat the clearance of the lower chamber about the receding rod ortubular contact is greater, tests have shown this to be not a criticalfactor; the important feature appearing to be that the division baffle Cor C, constitutes a step, either up or down, in the bore size of thearcing passage and a dividing means between the upper and lower chambersof the interrupter of my invention.

While there has been shown and described a particular embodiment of theinvention, it will be obvious to those skilled in the art that changesand modifications may be made without departing from the invention, andthat it is intended by the appended claims to cover all such changes andmodifications as fall within the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

l. A fluid-blast type of interrupting unit having means for drawing anarc and establishing a pressure therein comprising a composite assemblyof stacked insulating bafiie plates, an intermedaite one of said stackedplates constituting a division baffle fixedly positioned in saidassembly and sectionalizing said assembly into a first and secondchamber, said first chamber being located adjacent the point at whichthe arc is initiated, openings in said plates defining a main arcpassage extending through said chambers and said division bafiie, saidopenings further defining a first supplementary vented arcing passagefor said first chamber disposed adjacent said main arc passage on oneside of said division baffle and a second supplementary vented arcingpassage for said second chamber disposed adjacent said main arcingpassage on the opposite side of said division bafiie, a blast ductcommunicating betwen said chambers and adapted to direct a blast offluid across said are passage and into one of said supplementary arcingpassages, said supplementary arcing passages terminating in vents, thevent from said first supplementary arcing passage being substantiallylarger than the vents from said second supplementary arcing passage.

2. In a fluid blast interrupting unit having a generally fixed contactand a movable contact separable to draw an arc and establish a pressurewithin said unit, a composite assembly of stacked baffle plates, anintermediate one of said stacked plates constituting a division baffiesectionalizing said assembly into a first and a second chamber, saidfirst chamber being located between said second chamber and said fixedcontact, said plates having openings defining a main arc passagereceiving said movable contact and extending through said chambers andsaid division baffle, the portion of said main arc passage in one ofsaid chambers having a substantially greater clearance with respect tosaid movable contact than that portion of the main arc passage whichextends through said division baffle and the other of said chambers, afirst supplementary vented arcing passage for said 2,717,294 7 8 firstchamber disposed adjacent said main arc passage References Cited in thefile of this patent on one side of said division baifie, a secondsupplemen- UNITED STATES PATENTS tary vented arcing passage for saidsecond chamber disposed adjacent said main arc passage on the opposite1955216 whltnfry et P 17, 193 4 side of said division battle, a blastduct communicating 5 2,545,334 Balentme 13) 9 between said chambers andadapted to direct a blast of FOREIGN PATENTS fluid into one of saidsupplementary arcing passages, 389 882 Great Britain Mar 30 1933 saidsupplementary arcing passages terminating in vents, 452146 Great Britain1936 the vent from said first supplementary arcing passage n beingsubstantially larger than the vent from said second 10 supplementaryarcing passage.

